A couple of things that we found out you should not do (though they are quite obvious):

• Work with red chili peppers, not wash your hands and after dinner try to put in a contact lens. I ruined a perfectly new lens with such an action and could not tolerate a clean one (after thoroughly washing my hands) in my eye afterwards.
• Scare a vomiting cat. Matthijs just cleaned up a puke-trail across the room after scaring Melisse. He tried to prevent her walking onto the carpet by making a sudden move towards her. Result: Melisse racing over the carpet, onto the couch, up and over the cat-tree, past the open door to the litter box all the while puking. You can imagine the mess.